Method and apparatus for preventing rapid temperature variation during processing

ABSTRACT

In a method for fabricating a semiconductor device, a semiconductor wafer is thermally treated with a wafer treatment device. The semiconductor wafer is delivered with a conveyer to the wafer treatment device. The temperature of the conveyer is controlled to have an optimum temperature.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims the priority of Application No.H09-339648, filed Dec. 10, 1997 in Japan, the subject matter of which isincorporated herein by reference.

TECHNICAL FIELD OF THE INVENTION

[0002] The present invention relates to method and apparatus forfabricating a semiconductor device. More particularly, the presentinvention directs to method and apparatus for fabricating asemiconductor device, in which a semiconductor wafer is delivered by aconveyer to a wafer treatment device and is thermally treated.

BACKGROUND OF THE INVENTION

[0003] In a process for fabricating a semiconductor device, asemiconductor wafer is thermally treated. For example, in diffusionprocess, an electrode formed on a compound semiconductor wafer issintered.

[0004] A conventional sinter furnace includes a heating chamber, inwhich a semiconductor wafer is heated, and a cooling chamber, in whichthe semiconductor wafer is cooled down. In such a conventional sinterfurnace, a semiconductor wafer is conveyed by a delivery arm, between aloader cassette and the heating chamber; between the heating chamber andthe cooling chamber; and between the cooling chamber and an un-loadercassette.

[0005] Semiconductor wafers contained in the loader cassette arecontrolled in temperature at about 20° C. The heating chamber includes ahot plate controlled in temperature at 450° C. The cooling chamberincludes a cooling plate controlled in temperature at 20° C.

[0006] According to the conventional apparatus, a semiconductor wafer ofthe room temperature is rapidly heated up when the wafer is put onto theheating plate in the heating chamber. The temperature of thesemiconductor wafer changes too rapidly, and therefore, thesemiconductor wafer may be broken by heat-shock phenomenon. In addition,a semiconductor wafer, which has been heated in the heating chamber, israpidly cooled down when the wafer is taken out from the heatingchamber. That is because the delivery arm is at the room temperature ofabout 20° C., which is 430° C. different from the semiconductor wafer,which has been already heated. As a result, the semiconductor wafer maybe broken by cool-shock phenomenon. Once a semiconductor wafer isbroken, semiconductor devices formed thereon can not be used anymore.The above-described problems are remarkable and more serious to compoundtype of semiconductor wafers, such as GaAs wafers,

OBJECTS OF THE INVENTION

[0007] Accordingly, an object of the present invention is to provide amethod for fabricating a semiconductor device in which a semiconductorwafer is prevented from being broken, caused by rapid temperaturevariation.

[0008] Another object of the present invention is to provide anapparatus for fabricating a semiconductor device in which asemiconductor wafer is prevented from being broken, caused by rapidtemperature variation.

[0009] Additional objects, advantages and novel features of the presentinvention will be set forth in part in the description that follows, andin part will become apparent to those skilled in the art uponexamination of the following or may be learned by practice of theinvention. The objects and advantages of the invention may be realizedand attained by means of the instrumentalities and combinationsparticularly pointed out in the appended claims.

SUMMARY OF THE INVENTION

[0010] According to a first aspect of the present invention, a methodfor fabricating a semiconductor device includes the steps of: thermallytreating a semiconductor wafer with a wafer treatment device; deliveringthe semiconductor wafer with a conveyer to the wafer treatment device;and controlling the temperature of the conveyer to have an optimumtemperature.

[0011] According to a second aspect of the present invention, anapparatus for fabricating a semiconductor device, includes a wafertreatment device which applies a thermal treatment to a semiconductorwafer; a conveyer which delivers the semiconductor wafer to and from thewafer treatment device; and a controller which controls the temperatureof the conveyer to have an optimum temperature.

[0012] As described above, according to the present invention, theconveyer is controlled in temperature, therefore, it can be avoided thatthe temperature of the semiconductor wafer is changed too rapidly. As aresult, the semiconductor wafer is prevented from being broken due toheat-shock (rapid heating) or cool-shock (rapid cooling).

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 is a plan view illustrating a conventional sinter furnace.

[0014]FIG. 2 is a graph showing temperature variation of a semiconductorwafer that is processed the conventional sinter furnace.

[0015]FIG. 3 is a plan view illustrating a sinter furnace according to afirst preferred embodiment of the present invention.

[0016]FIG. 4 is a cross-sectional view taken on line A-A of FIG. 3.

[0017]FIG. 5 is a cross-sectional view showing the inside of a deliveryarm used in the sinter furnace of the first preferred embodiment.

[0018]FIG. 6 is an explanatory diagram showing the operation of an armunit used in the sinter furnace of the first preferred embodiment.

[0019]FIG. 7 is a graph showing temperature variation of a semiconductorwafer that is processed in the sinter furnace of the first preferredembodiment.

[0020]FIG. 8 is a plan view illustrating a sinter furnace according to asecond preferred embodiment of the present invention.

[0021]FIG. 9 is a cross-sectional view taken on line B-B in FIG. 8.

[0022]FIG. 10 is a cross-sectional view taken on line C-C in FIG. 8.

[0023]FIG. 11 is a cross-sectional view showing the inside of a deliveryarm of a first arm unit used in the sinter furnace of the secondpreferred embodiment.

[0024]FIG. 12 is a cross-sectional view showing the inside of a deliveryarm of a second arm unit used in the sinter furnace of the secondpreferred embodiment.

[0025]FIG. 13 is a graph showing temperature variation of asemiconductor wafer that is processed in the sinter furnace of thesecond preferred embodiment.

[0026]FIG. 14 is a plan view illustrating a sinter furnace according toa third preferred embodiment of the present invention.

[0027]FIG. 15 is a diagram showing the operation of an arm unit used inthe sinter furnace of the third preferred embodiment.

[0028]FIG. 16 is a graph showing temperature variation of asemiconductor wafer that is processed in the sinter furnace of the thirdpreferred embodiment.

[0029]FIG. 17 is a plan view illustrating a sinter furnace according toa fourth preferred embodiment of the present invention.

[0030]FIG. 18 is a cross-sectional view taken on line D-D in FIG. 17.

[0031]FIG. 19 is a cross-sectional view showing the inside of a deliveryarm of an arm unit used in the sinter furnace of the fourth preferredembodiment.

[0032]FIG. 20 is a graph showing the temperature variation of asemiconductor wafer, which is processed in the sinter furnace accordingto the fourth preferred embodiment of the present invention.

DETAILED DISCLOSURE OF THE INVENTION

[0033] For better understanding of the present invention, a conventionaltechnology is first described. FIG. 1 depicts a conventional sinterfurnace, which includes a heating chamber 1, a cooling chamber 2, aconveying arm 3, a loader cassette 5 and an un-loader cassette 6. In theheating chamber 1, a GaAs semiconductor wafer 4 is heated on a hotplate, kept at 450° C., in a nitrogen gas atmosphere. In the coolingchamber 2, the semiconductor wafer 4 is cooled by a cool plate, kept at20° C., in a nitrogen gas atmosphere. The semiconductor wafer 4 isdelivered by the conveying arm 3, which is made of SUS. In the loadercassette 5 and the un-loader cassette 6, semiconductor wafers have theroom temperature of about 20° C.

[0034]FIG. 2 is a graph showing temperature variation of thesemiconductor wafer 4, which is processed by the conventional sinterfurnace. When a semiconductor wafer 4 is conveyed by the conveying arm 3from the loader cassette 5 to the heating chamber 1, the semiconductorwafer 4 is heated in the heating chamber 1 for five minutes. The instantthe semiconductor wafer 4 is put on the hot plate (not shown) in theheating chamber 1, the semiconductor wafer is rapidly heated to 450° C.,as shown in FIG. 2.

[0035] After the heating treatment, the semiconductor wafer 4 isconveyed by the conveying arm 3 from the heating chamber 1 to thecooling chamber 2. The instant the semiconductor wafer 4 is in touchwith the conveying arm 3 of the room temperature, the semiconductorwafer 4 is rapidly cooled down, because the conveying arm 3 is more than400° C. different in temperature from the semiconductor wafer 4, whichhas been heated to 450° C.

[0036] According to the conventional apparatus, the semiconductor wafer4 of the room temperature is rapidly heated up when the wafer is putonto the hot plate in the heating chamber 1, and therefore, thesemiconductor wafer 4 may be broken by heat-shock phenomenon. Inaddition, a wafer, which has been heated in the heating chamber 1, israpidly cooled down when the wafer is picked up with the conveying arm3. As a result, the wafer may be broken by cool-shock phenomenon. Once asemiconductor wafer is broken, semiconductor devices formed on the wafercan not be used anymore.

[0037]FIG. 3 depicts a sinter furnace according to a first preferredembodiment of the present invention. FIG. 4 shows the cross-sectiontaken on line A-A of FIG. 3. The sinter furnace includes a heatingchamber 10, a cooling chamber 12, a conveying arm unit 20, a. loadercassette 16 and an un-loader cassette 18. In the heating chamber 10, aGaAs semiconductor wafer 14 is heated on a hot plate (not shown), whichis kept at 450° C., in a nitrogen gas atmosphere. In the cooling chamber12, the semiconductor wafer 14 is cooled on a cool plate (not shown),which is kept at 20° C., in a nitrogen gas atmosphere. During sinteringprocess, the semiconductor wafer 14 is delivered by the conveying armunit 20, which is made of SUS. In the loader cassette 16 and theun-loader cassette 18, semiconductor wafers have the room temperature ofabout 20° C.

[0038] The arm unit 20 includes a base arm 22, a delivery arm 24 androtation motors 26 and 28. The motor 26 is connected to one end of thebase arm 22 and turns (swings or pivots) the base arm 22 on the axisthereof. The motor 28 is connected to the other end of the base arm 22and to one end of the delivery arm 24 and turns (swings or pivots) thedelivery arm 24 on the axis thereof. The semiconductor wafer 14 isplaced on the other end of the delivery arm 24. The delivery arm 24 isconnected to a controller 34 via a flexible cable 36. The base arm 22and the delivery arm 24 are driven independently from each other, sothat the semiconductor wafer 14 can be delivered only by the deliveryarm 24.

[0039] As shown in FIG. 4, the heating chamber 10 is provided with anelevation motor 30 and elevation pins 32. The elevation pins 32 extendvertically through the heating chamber 10 to reach the bottom surface ofthe semiconductor wafer 14. The elevation motor 30 drives the elevationpins 32 up and down so that the semiconductor wafer 14 is deliveredbetween the delivery arm 24 and the hot plate (not shown) in the heatingchamber 10. In the same manner as the heating chamber 10, the coolingchamber 12 is provided with an elevation motor (not shown) and elevationpins (not shown), as well.

[0040]FIG. 5 depicts the inside structure of the delivery arm 24according to the first preferred embodiment of the present invention.The delivery arm 24 is provided therein with a heating coil 38 and athermocouple 40. The heating coil 38 is connected via a flexible wire 42to the controller 34, shown in FIG. 4. The thermocouple 40 is connectedvia a flexible wire 44 to the controller 34. The wires 42 and 44 areincluded in the flexible cable 36 so that the flexible wires 42 and 44do not block the passage of the base arm 22 and the delivery arm 24.

[0041] The heating coil 38 generates heat in response to electriccurrent supplied from the controller 34 through the flexible wire 42, sothat the delivery arm 24 is heated to about 200° C. Basically, thedelivery arm 24 is controlled in temperature at 200° C. throughout thesintering process. The thermocouple 40 detects the temperature of thedelivery arm 24 and supplies the corresponding output signal to thecontroller 34 through the flexible wire 44. In response to the outputsignal of the thermocouple 40, the controller 34 controls the amount ofcurrent to be supplied through the flexible wire 42 to the heating coil38, so that the delivery arm 24 is controlled at an optimum temperature(200° C.).

[0042]FIG. 6 shows the route along which the semiconductor wafer 14 isdelivered, according to the first preferred embodiment of the presentinvention. FIG. 7 is a graph showing temperature variation of thesemiconductor wafer 14, which is processed in the sinter furnace of thefirst preferred embodiment of the present invention. When thesemiconductor wafer 14 is picked up with the delivery arm 24 from theloader cassette 16, the semiconductor wafer 14 is delivered toward theheating chamber 10. During the delivery of the semiconductor wafer 14between the loader cassette 16 and the heating chamber 10, as indicatedby a broken line of {circle over (1)}, the semiconductor wafer 14 ispre-heated to 150-200° C. on the delivery arm 24. The delivery arm 24delivers the semiconductor wafer 14 relatively slowly so that thesemiconductor wafer 14 is enough preheated.

[0043] When the delivery arm 24 is positioned above the heating chamber10, the elevation motor 30 moves up the elevation pins 32 so as to reachthe semiconductor wafer 14, and the delivery arm 24 slides back not toblock the passage of the semiconductor wafer 14. When the delivery arm24 is completely apart from the heating chamber 10, the elevation motor30 moves down the elevation pins 32 so that the semiconductor wafer 14is set on the hot plate in the heating chamber 10. The semiconductorwafer 14 is heated on the hot plate (not shown) of 450° C. in a nitrogengas atmosphere for five minute. When the semiconductor wafer 14 isplaced on the hot plate, the semiconductor wafer 14 has been alreadyheated to 150-200° C. As a result, the semiconductor wafer 14 is notheated too rapidly to 450° C., as shown in FIG. 7. Therefore, it isavoided that the semiconductor wafer 14 is broken due to heat-shockphenomenon.

[0044] After the heating treatment in the heating chamber 10, theelevation motor 30 moves up the elevation pins 32 so that the elevationpins 32 lifts the semiconductor wafer 14 apart from the heating chamber10. When the semiconductor wafer 14 is lifted up from the heatingchamber 10, the delivery arm 24 is slid under the semiconductor wafer14, then the elevation pins 32 goes down so that the semiconductor wafer14 is placed on the delivery arm 24. When the semiconductor wafer 14 of450° C. is in touch with the delivery arm 24 of 200° C., thesemiconductor wafer 14 is cooled down to around 150 to 200° C. Becausethe temperature difference between the semiconductor wafer 14 and thedelivery arm 24 is about 250° C., the semiconductor wafer 14 is notcooled down too rapidly. Therefore, it is avoided that the semiconductorwafer 14 is broken due to cool-shock phenomenon.

[0045] Next, the semiconductor wafer 14 is delivered by the delivery arm24 from the heating chamber 10 to the cooling chamber 12, as indicatedby a broken line of {circle over (2)}. In the cooling chamber 12, thesemiconductor wafer 14 is cooled down on the cool plate of 20° C. Thecooling treatment is carried out for five minutes in a nitrogen gasatmosphere. After the cooling treatment, the delivery arm 24 picks upthe semiconductor wafer 14 and delivers it to the un-loader cassette 18,as indicated by a broken line of {circle over (3)}. In the coolingchamber 12, the semiconductor wafer 14 is conveyed between the deliveryarm 24 and the cool plate in the same manner as the heating chamber 10.

[0046] As described above, according to the first preferred embodimentof the present invention, the delivery arm 24 is controlled intemperature, therefore, it can be avoided that the temperature of thesemiconductor wafer 14 is changed too rapidly. As a result, thesemiconductor wafer 14 is prevented from being broken due to heat-shock(rapid heating) or cool-shock (rapid cooling).

[0047]FIG. 8 depicts a sinter furnace according to a second preferredembodiment of the present invention. FIG. 9 is a cross-sectional viewtaken on line B-B in FIG. 8. FIG. 10 is a cross-sectional view taken online C-C in FIG. 8. The sinter furnace of the second preferredembodiment includes a heating chamber 110, a cooling chamber 112, afirst conveying arm unit 120, a second conveying arm unit 150, a loadercassette 116 and an un-loader cassette 118. In the heating chamber 110,a GaAs semiconductor wafer 114 is heated on a hot plate (not shown),which is kept at 450° C., in a nitrogen gas atmosphere. In the coolingchamber 112, the semiconductor wafer 114 is cooled on a cool plate (notshown), which is kept at 20° C., in a nitrogen gas atmosphere. Duringsintering process, the semiconductor wafer 114 is delivered by the firstand second conveying arm units 120 and 150, which are made of SUS. Inthe loader cassette 116 and the un-loader cassette 118, semiconductorwafers have the room temperature of about 20° C.

[0048] The first arm unit 120 includes a base arm 122, a delivery arm124 and motors 126 and 128. The motor 126 is connected to one end of thebase arm 122 and turns (swings or pivots) the base arm 122 on the axisthereof. The motor 128 is connected to the other end of the base arm 122and to one end of the delivery arm 124 and turns (swings or pivots) thedelivery arm 124 on the axis thereof. The semiconductor wafer 114 isplaced on the other end of the delivery arm 124, The delivery arm 124 isconnected to a controller 134 via a flexible cable 136. The base arm 122and the delivery arm 124 are driven independently from each other, sothat the semiconductor wafer 114 can be delivered only by the deliveryarm 124.

[0049] The second arm unit 150 includes a base arm 152, a delivery arm154 and motors 156 and 158. The motor 156 is connected to one end of thebase arm 152 and turns (swings or pivots) the base arm 152 on the axisthereof. The motor 158 is connected to the other end of the base arm 152and to one end of the delivery arm 154 and turns (swings or pivots) thedelivery arm 154 on the axis thereof. The semiconductor wafer 114 isplaced on the other end of the delivery arm 154. The delivery arm 154 isconnected to a controller 164 via a flexible pipe 168. The base arm 152and the delivery arm 154 are driven independently from each other, sothat the semiconductor wafer 114 can be delivered only by the deliveryarm 154.

[0050] As shown in FIG. 9, the heating chamber 110 is provided with anelevation motor 130 and elevation pins 132. The elevation pins 132extend vertically through the heating chamber 110 to reach the bottomsurface of the semiconductor wafer 114. The elevation motor 130 drivesthe elevation pins 132 up and down so that the semiconductor wafer 114is carried between the delivery arm 124 and the hot plate (not shown) inthe heating chamber 110.

[0051] As shown in FIG. 10, the cooling chamber 112 is provided with anelevation motor 160 and elevation pins 162. The elevation pins 162extend vertically through the cooling chamber 112 to reach the bottomsurface of the semiconductor wafer 114. The elevation motor 160 drivesthe elevation pins 162 up and down so that the semiconductor wafer 114is carried between the delivery arm 124 and the cool plate (not shown)in the cooling chamber 112, and between the delivery arm 154 and thecool plate.

[0052]FIG. 11 depicts the inside structure of the delivery arm 124 ofthe first conveying arm unit 120 according to the second preferredembodiment of the present invention. The delivery arm 1.24 is providedtherein with a heating coil 138 and a thermocouple 140. The heating coil138 is connected via a flexible wire 142 to the controller 134, shown inFIG. 9. The thermocouple 140 is connected via a flexible wire 144 to thecontroller 134. The flexible wires 142 and 144 are included in theflexible cable 136 so that the flexible wires 142 and 144 do not blockthe passage of the base arm 122 and the delivery arm 124.

[0053] The heating coil 138 generates heat in response to electriccurrent supplied from the controller 134 through the flexible wire. 142,so that the delivery arm 124 is heated to about 200′. The thermocouple140 detects the temperature of the delivery arm 124 and supplies thecorresponding output signal to the controller 134 through the flexiblewire 144. In response to the output signal of the thermocouple 140, thecontroller 134 controls the amount of current to be supplied through theflexible wire 142 to the heating coil 138, so that the delivery arm 124is controlled at an optimum temperature.

[0054]FIG. 12 depicts the inside structure of the delivery arm 154 ofthe second conveying arm unit 150 according to the second preferredembodiment of the. present invention. The delivery arm 154 is providedtherein with a cooling pipe 170 and a thermocouple 172. The cooling pipe170 is connected via a flexible pipe 168 to the controller 164, as shownin FIG. 10. The thermocouple 172 is connected via a flexible wire 174 tothe controller 164. The ends of the cooling pipe 170 and the flexiblewire 174 are contained in the flexible pipe 164 so that the cooling pipe170 and the flexible wire 172 do not block the passage of the base arm152 and the delivery arm 154.

[0055] Cooling liquid, such as water, is traveling in the cooling pipe170 so that the delivery arm 154 is controlled in temperature at about20° C. The thermocouple 172 detects the temperature of the delivery arm154 and supplies the corresponding output signal to the controller 164through the flexible wire 174. In response to the output signal of thethermocouple 172, the controller 164 controls the temperature of thecooling liquid traveling in the cooling pipe 170, so that the deliveryarm 154 is controlled at an optimum temperature.

[0056]FIG. 13 is a graph showing temperature variation of thesemiconductor wafer 114, which is processed in the sinter furnaceaccording to the second preferred embodiment of the present invention.In this embodiment, the first conveying arm unit 120 is used forconveying the semiconductor wafer 114 between the loader cassette 116and the heating chamber 110, and between the heating chamber 110 and thecooling chamber 112. On the other hand, the second conveying arm unit150 is used for conveying the semiconductor wafer 114 between thecooling chamber 112 and the un-loader cassette 118.

[0057] In operation, the semiconductor wafer 114 is picked up with thedelivery arm 124 of the first conveying arm unit 120 from the loadercassette 116, and delivered toward the heating chamber 110. During thedelivery of the semiconductor wafer 114 between the loader cassette 116and the heating chamber 110, the semiconductor wafer 114 is pre-heatedto 150-200° C. on the delivery arm 124. The delivery arm 124 deliversthe semiconductor wafer 114 relatively slowly so that the semiconductorwafer 114 is pre-heated enough.

[0058] When the delivery arm 124 is positioned just above the heatingchamber 110, the elevation motor 130 moves up the elevation pins 132 soas to reach the semiconductor wafer 114, and the delivery arm 124 slidesback not to block the passage of the semiconductor wafer 114. When thedelivery arm 124 is completely apart from the heating chamber 110, theelevation motor 130 moves down the elevation pins 132 so that thesemiconductor wafer 114 is arranged on the hot plate (not shown) in theheating chamber 110. The semiconductor wafer 114 is heated on the hotplate (not shown) in a nitrogen gas atmosphere for five minute. When thesemiconductor wafer 114 is placed on the hot plate, the semiconductorwafer 114 has been already pre-heated to 150-200° C. As a result, thesemiconductor wafer 114 is not heated too rapidly to 450° C., as shownin FIG. 13. Therefore, the semiconductor wafer 114 is prevented frombeing broken due to heat-shock phenomenon.

[0059] After the heating treatment in the heating chamber 110, theelevation motor 130 moves up the elevation pins 132 so that theelevation pins 132 lifts up the semiconductor wafer 114 apart from theheating chamber 110. When the semiconductor wafer 114 is lifted up fromthe heating chamber 110, the delivery arm 124 is slid under thesemiconductor wafer 114, then the elevation pins 132 goes down so thatthe semiconductor wafer 114 is placed on the delivery arm 124. When thesemiconductor wafer 114 of 450° C. is in touch with the delivery arm 124of 200° C., the semiconductor wafer 114 is cooled down to around150-200° C. Because the temperature difference between the semiconductorwafer 114 and the delivery arm 124 is about 250° C., the semiconductorwafer 114 is not cooled down too rapidly, Therefore, the semiconductorwafer 114 is prevented from being broken due to cool-shock phenomenon.

[0060] Next, the semiconductor wafer 114 is delivered by the deliveryarm 124 from the heating chamber 110 to the cooling chamber 112.

[0061] When the delivery arm 124 is positioned above the cooling chamber112, the elevation motor 160 moves up the elevation pins 162 so as toreach the semiconductor wafer 114, and the delivery arm 124 slides backnot to block the passage of the semiconductor wafer 114. When thedelivery arm 124 is completely apart from the cooling chamber 112, theelevation motor 160 moves down the elevation pins 162 so that thesemiconductor wafer 114 is arranged on the cool plate (not shown) in thecooling chamber 112. The semiconductor wafer 114 is cooled on the coolplate (not shown) in a nitrogen gas atmosphere for five minute.

[0062] After the cooling treatment, the elevation motor 160 moves up theelevation pins 162 so that the elevation pins 162 lifts thesemiconductor wafer 114 apart from the cooling chamber 112. When thesemiconductor wafer 114 is lifted up from the cooling chamber 112, thedelivery arm 154 of the second conveying arm unit 150 is slid under thesemiconductor wafer 114. Then, the elevation pins 162 goes down so thatthe semiconductor wafer 114 is placed on the delivery arm 154. In thiscase, the semiconductor wafer 114 of 20° C. is in touch with thedelivery arm 154 of 20° C., so that there is no temperature differencebetween them. Therefore, the semiconductor wafer 114 is prevented frombeing broken due to cool-shock phenomenon.

[0063] Next, the semiconductor wafer 114 is delivered by the deliveryarm 154 of the second conveying arm unit 150 to the un-loader cassette118.

[0064] As described above, according to the second preferred embodimentof the present invention, the delivery arm 124 of the first conveyingarm unit 120 is controlled in temperature at 200° C. Therefore, thesemiconductor wafer 114 is prevented from being broken due to heat-shock(rapid heating) or cool-shock (rapid cooling).

[0065] Further, according to the second preferred embodiment of thepresent invention, the delivery arm 154 of the second conveying arm unit150 is controlled in temperature at 20° C. Therefore, it can be avoidedthat the temperature of the semiconductor wafer 114 is changed toorapidly, when the semiconductor wafer 114 is conveyed from the coolingchamber 112 to the un-loader cassette 118.

[0066]FIG. 14 depicts a sinter furnace according to a third preferredembodiment of the present invention. The sinter furnace includes aheating chamber 110, a cooling chamber 112, a first conveying arm unit120, a second conveying arm unit 150, an intermediate chamber 238, aloader cassette 116 and an un-loader cassette 118. In the heatingchamber 110, a Gas semiconductor wafer 114 is heated on a hot plate (notshown), which is kept at 450° C., in a nitrogen gas atmosphere. In thecooling chamber 112, the semiconductor wafer 114 is cooled on a coolplate (not shown), which is kept at 20° C, in a nitrogen gas atmosphere.During sintering process, the semiconductor wafer 114 is delivered bythe first and second conveying arm units 120 and 150, which are made ofSUS. In the loader cassette 116 and the un-loader cassette 118,semiconductor wafers have the room temperature of about 20° C.

[0067] The detailed structure of the first and second arm units 120 and150, the heating chamber 110, the cooling chamber 112, the loadercassette 1 16 and the un-loader cassette 118 correspond to those in thesecond preferred embodiment, shown in FIGS. 8-12. The same descriptionfor those elements are not repeated.

[0068] The intermediate chamber 238 includes a heat plate controlled intemperature at 150° C., so that the semiconductor wafer 114 placedtherein is pre-heated before the heating treatment of the heatingchamber 110 and pre-cooling before the cooling treatment of the cooingchamber 112.

[0069]FIG. 15 shows the route along which the semiconductor wafer 114 isdelivered in the sinter furnace according to the third preferredembodiment of the present invention. FIG. 16 shows temperature variationof the semiconductor wafer 114, which is processed in the sinter furnaceaccording to the third preferred embodiment of the present invention.

[0070] In this embodiment, the first conveying arm unit 120, providedwith the heating mechanism, is used for conveying the semiconductorwafer 114 between the intermediate chamber 238 and the heating chamber110, as indicated by broken lines {circle over (2)} and {circle over(3)}. On the other hand, the second conveying arm unit 150, providedwith the cooling mechanism, is used for conveying the semiconductorwafer 114 from the loader cassette 116 to the intermediate chamber 238,as indicated by a broken line {circle over (1)}; from the intermediatechamber 238 to the cooling chamber 112, as indicated by a broken line{circle over (4)}; and from the cooling chamber 112 to the un-loadercassette 118, as indicated by a broken line {circle over (5)}.

[0071] In operation, first, the semiconductor wafer 114 is delivered bythe delivery arm 154 of the second conveying arm unit 150 from theloader cassette 116 to the intermediate chamber 238, as indicated bybroken line {circle over (1)}. When the semiconductor 114 is placed onthe delivery arm 154, the delivery arm 154 has been controlled at 20°C., which is corresponding to the current temperature of thesemiconductor wafer 114. In the intermediate chamber 238, thesemiconductor wafer 114 is gradually heated to 150° C. in a nitrogen gasatmosphere for five minutes.

[0072] Next, the first conveying arm unit 120 delivers the semiconductorwafer 114 from the intermediate chamber 238 to the heating chamber 110,as indicated by broken line {circle over (2)}. When the semiconductorwafer 114 is placed on the delivery arm 124, the temperature differencebetween them is about 50° C. In the heating chamber 110, thesemiconductor wafer 114 is heated on the hot plate (not shown) in anitrogen gas atmosphere for five minute. When the semiconductor wafer114 is placed on the hot plate of the heating chamber 110, thesemiconductor wafer 114 has been already heated to 150-200° C. by thedelivery arm 124 of the first conveying arm unit 120. As a result, thetemperature difference between the semiconductor wafer 114 and the hotplate is 250-300° C. Therefore, the semiconductor wafer 114 is notheated too rapidly to 450° C., as shown in FIG. 16. The semiconductorwafer 114 is prevented from being broken due to heat-shock phenomenon.

[0073] After the heating treatment in the heating chamber 110, the firstconveying arm unit 120 delivers the semiconductor wafer 114 to theintermediate chamber 238 again, as indicated by broken line {circle over(3)}. When the semiconductor wafer 114. of 450° C. is in touch with thedelivery arm 124 of 200° C., the semiconductor wafer 114 is cooled downto around 150-200° C. Because the temperature difference between thesemiconductor wafer 114 and the delivery arm 124 is about 250° C., thesemiconductor wafer 114 is not cooled down too rapidly. Therefore, thesemiconductor wafer 114 is prevented from being broken due to cool-shockphenomenon.

[0074] In the intermediate chamber 238, the semiconductor wafer 114 iscontrolled in temperature at 150° C. When the semiconductor wafer 114 isset in the intermediate chamber 238, there is no temperature differencebetween them. After the intermediate treatment, the semiconductor wafer114 is delivered by the second conveying arm unit 150 to the coolingchamber 112, as indicated by a broken line {circle over (4)}. In thecooling chamber 112, the semiconductor wafer 114 is cooled on the coolplate (not shown) in a nitrogen gas atmosphere for five minute.

[0075] After the cooling treatment, the second conveying arm unit 150delivers the semiconductor wafer 114 to the un-loader cassette 118, asindicated by broken line {circle over (5)}. In this case, thesemiconductor wafer 114 of 20° C. is in touch with the delivery arm 154of 20° C., so that no temperature difference is made between them.Therefore, the semiconductor wafer 114 is prevented from being brokendue to cool-shock phenomenon.

[0076] As described above, according to the third preferred embodimentof the present invention, the same advantages as the first and secondpreferred embodiments can be obtained. That is, it can be avoided thatthe temperature of the semiconductor wafer 114 is changed too rapidly.As a result, the semiconductor wafer 114 is prevented from being brokendue to heat-shock (rapid heating) or cool-shock (rapid cooling).

[0077]FIG. 17 depicts a sinter furnace according to a fourth preferredembodiment of the present invention. FIG. 18 shows a cross-section takenon line D-D in FIG. 17. The sinter furnace according to the fourthpreferred embodiment includes a heating chamber 310, a cooling chamber312, a conveying arm unit 320, an intermediate chamber 338, a loadercassette 316 and an un-loader cassette 318. In the heating chamber 310,a GaAs semiconductor wafer 314 is heated on a hot plate (not shown),which is kept at 450° C., in a nitrogen gas atmosphere. In the coolingchamber 312, the semiconductor wafer 314 is cooled on a cool plate (notshown), which is kept at 20° C., in a nitrogen gas atmosphere. Duringsintering process, the semiconductor wafer 314 is delivered by theconveying arm unit 320, which is made of SUS. In the loader cassette,316 and the un-loader cassette 318, semiconductor wafers have the roomtemperature of about 20° C.

[0078] The conveying arm unit 320 includes a base arm 322, a deliveryarm 324 and motors 326 and 328. The motor 326 is connected to one end ofthe base arm 322 and turns (swings or pivots) the base arm 322 on theaxis thereof. The motor 328 is connected to the other end of the basearm 322 and to one end of the delivery arm 324 and turns (swings orpivots) the delivery arm 324 on the axis thereof. The semiconductorwafer 314 is placed on the other end of the delivery arm 324. Thedelivery arm 324 is connected to a controller 334 via a flexible tube336. The base arm 322 and the delivery arm 324 are driven independentlyfrom each other, so that the semiconductor wafer 314 can be deliveredonly by the delivery arm 324.

[0079] As shown in FIG. 18, the heating chamber 310 is provided with anelevation motor 330 and elevation pins 332. The elevation pins 32 extendvertically through the heating chamber 310 to reach the bottom surfaceof the semiconductor wafer 314. The elevation motor 330 drives theelevation pins 332 up and down so that the semiconductor wafer 314 isdelivered between the delivery arm 324 and the hot plate (not shown) inthe heating chamber 310. In the same manner as the heating chamber 310,the cooling chamber 312 is provided with an elevation motor (not shown)and elevation pins.(not shown), as well.

[0080]FIG. 19 shows the inside structure of the delivery arm 324 of theconveying arm unit 320 according to the fourth preferred embodiment ofthe present invention. The delivery arm 324 is provided therein with aheating coil 388, a cooling pipe 370 and a thermocouple 372. The heatingcoil 388 is connected via a flexible wire 390 to the controller 334,shown in FIG. 18. The ends of the cooling pipe 370 are connected via theflexible tube 336 to the controller 334. The thermocouple 372 isconnected via a flexible wire 374 to the controller 334. The flexiblewires 374 and 390, and the cooling pipe 370 are included in the flexibletube 336 so that the flexible wires 374 and 390 and the cooling pipe 370do not block the passage of the base arm 322 and the delivery arm 324.

[0081] The heating coil 388 generates heat. in response to electriccurrent supplied from the controller 334 through the flexible wire 390,so that the delivery arm 324 can be heated to 450° C. The thermocouple372 detects the temperature of the delivery arm 324 and supplies thecorresponding output signal to the controller 334 through the flexiblewire 374. In response to the output signal of the thermocouple 372, thecontroller 334 controls the amount of current to be supplied through theflexible wire 390 to the heating coil 388, so that the delivery arm 324is controlled at an optimum temperature.

[0082] Cooling liquid, such as water, is traveling in the cooling pipe370 so that the delivery arm 324 can be controlled in temperature toabout 20° C. In response to the output signal of the thermocouple 372,the controller 334 controls the temperature of the cooling liquidtraveling in the cooling pipe 370, so that the delivery arm 324 iscontrolled at an optimum temperature.

[0083] The controller 334 selectively operates a current source (notshown), supplying electric current to the heating coil 388, and a pump(not shown), supplying the cooling liquid to the cooling pipe 370. Inother words, the controller 334 controls the delivery arm 324 to havethe optimum temperature all the time during delivery of thesemiconductor waver 314.

[0084]FIG. 20 shows the temperature variation of the semiconductor wafer314, which is processed in the sinter furnace according to the fourthpreferred embodiment of the present invention.

[0085] In operation, first, the delivery arm 324 of the conveying armunit 320 delivers the semiconductor wafer 314 from the loader. cassette316 to the intermediate chamber 338. When the semiconductor wafer 314 isput on the delivery arm 324, the delivery arm 324 is controlled intemperature at 20° C., corresponding to the current temperature of thesemiconductor wafer 314. In other words, there is no temperaturedifference between the semiconductor wafer 314 and the delivery arm 324.Once the semiconductor wafer 314 is set on the delivery arm 324, thecontroller 334 starts operating the heating coil 388 to control thetemperature of the delivery arm 324 until 150° C., which iscorresponding to the temperature in the intermediate chamber 338. In theintermediate chamber 338, the semiconductor wafer 314 is controlled intemperature at 150° C. in a nitrogen gas atmosphere for five minutes.

[0086] Next, the delivery arm 324 delivers the semiconductor wafer 314from the intermediate chamber 338 to the heating chamber 310. When thesemiconductor wafer 314 is put on the delivery arm 324, the delivery arm324 has been controlled in temperature at 150° C., which iscorresponding to the current temperature of the semiconductor wafer 314.During the delivery from the intermediate chamber 338 to the heatingchamber 310, the controller 334 operates the heating coil 388 to controlthe temperature of the delivery arm 324 until 450° C., which iscorresponding to the temperature in the heating chamber 310. Thus, notemperature difference is made when the semiconductor wafer 314 isdelivered in the heating chamber 310. In the heating chamber 310, thesemiconductor wafer 314 is heated on the hot plate (not shown) in anitrogen gas atmosphere for five minute.

[0087] After the heating treatment, the delivery arm 324 delivers thesemiconductor wafer 314 to the intermediate chamber 338. When thesemiconductor wafer 314 of 450° C. is put on the delivery arm 324, thedelivery arm 324 has been controlled at 450° C. During the deliverybetween the heating chamber 310 and the intermediate chamber 338, thecontroller 334 operates the cooling system (370) to control thetemperature of the delivery arm 324 until 150° C., which iscorresponding to the temperature. in the intermediate chamber 338. Inthe intermediate chamber 338, the semiconductor wafer 314 is controlledin temperature at 150° C. in a nitrogen gas atmosphere for five minutes.

[0088] After the intermediate treatment, the delivery arm 324 deliversthe semiconductor wafer 314 to the cooling chamber 312. When thesemiconductor wafer 314 is place on the delivery arm 324, the deliveryarm 324 has been controlled in temperature at 150° C., which iscorresponding to the current temperature of the semiconductor wafer 314.During the delivery between the intermediate chamber 338 and the coolingchamber 312, the controller 334 controls the temperature of the deliveryarm 324 until 20° C., which is corresponding to the temperature in thecooling chamber 312. In the cooling chamber 312, the semiconductor wafer314 is cooled on the cool plate (not shown) at 20° C. in a nitrogen gasatmosphere for five minutes.

[0089] After the cooling treatment, the semiconductor wafer 314 isdelivered to the un-loader cassette 318. When the semiconductor wafer314 is set on the delivery arm 324, the delivery arm 324 has beencontrolled in temperature at 20° C., which is corresponding to thecurrent temperature of the semiconductor wafer 314.

[0090] As described above, according to the fourth preferred embodimentof the present invention, the delivery arm 324 is controlled to have thesame temperature as the semiconductor wafer 314 every time when thoseare touch with each other. In other words, no temperature difference ismade between the semiconductor wafer 314 and the delivery arm 324.Therefore, it is prevented that the semiconductor wafer 314 is brokendue to heat-shock (rapid heating) or cool-shock (rapid cooling).

[0091] It will be understood that the above description of the presentinvention is susceptible to various modifications, changes andadaptations, and the same are intended to be comprehended with themeaning and range of equivalents of the appended claims.

[0092] The present invention is applicable not only to a single waferprocessing type, but also, to a batch processing type of sinter furnace.The present invention is applicable not only to a sinter furnace, butalso, to a CVD apparatus, a dry-etching apparatus, and the like.

What is claimed is:
 1. A method for fabricating a semiconductor device,comprising the steps of: thermally treating a semiconductor wafer with awafer treatment device; delivering the semiconductor wafer with aconveyer to the wafer treatment device; and controlling the temperatureof the conveyer to have an optimum temperature.
 2. The method accordingto claim 1, wherein the semiconductor wafer is heated by the wafertreatment device to a predetermined temperature.
 3. The method accordingto claim 2, wherein the conveyer is heated so as to decrease thetemperature difference from the semiconductor wafer.
 4. The methodaccording to claim 1, wherein the semiconductor wafer is cooled by thewafer treatment device.
 5. The method according to claim 4, wherein theconveyer is cooled so as to decrease the temperature difference from thesemiconductor wafer.
 6. An apparatus for fabricating a semiconductordevice, comprising: a wafer treatment device which applies a thermaltreatment to a semiconductor wafer; a conveyer which delivers thesemiconductor wafer to and from the wafer treatment device; and acontroller which controls the temperature of the conveyer to have anoptimum temperature.
 7. The apparatus according to claim 6, wherein thewafer treatment device comprises a wafer heater, which heats thesemiconductor wafer to a predetermined temperature.
 8. The apparatusaccording to claim 6, wherein the conveyer comprises a delivery arm onwhich the semiconductor wafer is placed.
 9. The apparatus according toclaim 8, wherein the controller comprises a conveyer heater which heatsthe conveyer to reduce the temperature difference from the semiconductorwafer.
 10. The apparatus according to claim 9, wherein the wafertreatment device comprises a wafer cooler which cools the semiconductorwafer to a predetermined temperature, and the controller comprises aconveyer cooler which cools the conveyer to reduce the temperaturedifference from the semiconductor wafer.
 11. An apparatus forfabricating a semiconductor device, comprising: a wafer heater whichheats a semiconductor wafer to a first temperature; a wafer cooler whichcools the semiconductor wafer, which has been heated by the waferheater, to a second temperature; a wafer conveying arm which deliversthe semiconductor wafer; and an arm heater which heats the waferconveying arm to have an optimum temperature, determined between thefirst and second temperatures.
 12. The apparatus according to claim 11,wherein the semiconductor wafer is a compound semiconductor wafer. 13.The apparatus according to claim 11, wherein the arm heater comprises aheater coil which is provided in the wafer conveying arm to produce heatin response to electric current.
 14. The apparatus according to claim11, further comprising: a sensor which detects the temperature of thewafer conveying arm; and a controller which controls the temperature ofthe arm in response to an output signal from the sensor.
 15. Anapparatus for fabricating a semiconductor device, comprising: a waferheater which heats a semiconductor wafer to a first temperature; a wafercooler which cools the semiconductor wafer, which has been heated by thewafer heater, to a second temperature; first and second conveying armswhich deliver the semiconductor wafer; an arm heater which heats thefirst conveying arm to have an optimum temperature, determined betweenthe first and second temperatures; and an arm cooler which cools thesecond conveying arm to have an optimum temperature.
 16. The apparatusaccording to claim 15, wherein the semiconductor wafer is a compoundsemiconductor wafer.
 17. The apparatus according to claim 15, whereinthe arm heater comprises a heater coil which is provided in the firstconveying arm to produce heat in response to electric current.
 18. Theapparatus according to claim 17, further comprising: a first sensorwhich detects the temperature of the first conveying arm; and acontroller which controls the temperature of the first conveying arm inresponse to an output signal from the first sensor.
 19. The apparatusaccording to claim 15, wherein the arm cooler comprises a circular pathprovided in the second conveying arm, cooling liquid running in thecircular path.
 20. The apparatus according to claim 19, furthercomprising: a second sensor which detects the temperature of the secondconveying arm; and a controller which controls the temperature of thesecond conveying arm in response to an output signal from the secondsensor.
 21. The apparatus according to claim 15, further comprising: anintermediate chamber in which the semiconductor wafer is controlled intemperature at between the first and second temperature, wherein thesemiconductor wafer is delivered to the intermediate chamber before theheating treatment by the wafer heater, and before the cooling treatmentby the wafer cooler.
 22. The apparatus according to claim 21, whereinthe first conveying arm delivers the semiconductor wafer between theintermediate chamber and the wafer heater; and the second conveying armdelivers the semiconductor wafer to the intermediate chamber, and fromthe intermediate chamber to the wafer cooler.
 23. An apparatus forfabricating a semiconductor device, comprising: a wafer heater whichheats a semiconductor wafer to a first temperature; a wafer cooler whichcools the semiconductor wafer to a second temperature; a conveying armwhich delivers the semiconductor wafer; and a temperature controllerwhich controls the temperature of the conveying arm to have the optimumtemperature.
 24. The apparatus according to claim 22, wherein thesemiconductor wafer is a compound semiconductor wafer.
 25. The apparatusaccording to claim 23, wherein the temperature controller comprises anarm heater which heats the conveying arm; and an arm cooler which coolsthe conveying arm, wherein the arm heater and the arm cooler isselectively operated.
 26. The apparatus according to claim 25, whereinthe arm heater comprises a heater coil which is provided in theconveying arm to produce heat in response to electric current.
 27. Theapparatus according to claim 25, wherein the arm cooler comprises acircular path provided in the conveying arm, cooling liquid running inthe circular path.
 28. The apparatus according to claim 25, furthercomprising: an intermediate chamber in which the semiconductor wafer iscontrolled in temperature of between the first and second temperature,wherein the semiconductor wafer is delivered to the intermediate chamberbefore the heating treatment by the wafer heater, and before the coolingtreatment by the wafer cooler.